There is a request for a motor control apparatus that controls driving of an electric motor for an electric power steering apparatus mounted on a vehicle, an electric motor for an electric brake device, an electric drive motor for an electric vehicle or a hybrid vehicle, or the like can continue the driving of these electric motors, even if there is an abnormality in a motor control system.
In order to respond the above-described request, it is proposed that a multi-phase motor winding of a multi-phase electric motor is duplicated, for example, the duplicated multi-phase motor windings are supplied with currents from individual inverter units, a control apparatus for a multi-phase rotary machine and an electric power steering using the same are provided with a failure control means that specifies a failed switching means in which an off-failure (i.e. an open failure) occurs when this failure occurs in a switching means of one of the inverter units and thus the switch means cannot be in a conduction state, and controls a switching means other than the failed switching means and a normal inverter unit other than a failed inverter unit including the failed switching means (see PTL 1, for example).